1. Field of the Invention
This invention relates to gas-fired appliances such as water heaters, space heaters and fireplaces and, more particularly, to a device for controlling components commonly found in gas-fired appliances, namely, dampers and valves.
2. Disclosure of Related Art
In a conventional gas-fired appliance a gas pipe delivers a fuel gas, such as natural gas, from a fuel source to both a pilot burner and to a main burner that are disposed proximate, or within, a combustion chamber. The gas pipe includes a pair of valves disposed within the gas pipe. The first valve controls the flow of fuel gas from the fuel source to the pilot burner. The second valve controls the flow of fuel gas to the main burner.
The pilot burner is provided to ignite fuel gas entering the main burner and may comprise a standing pilot burner or an intermittent pilot burner. If the pilot flame is extinguished for any reason, the valve between the fuel source and the pilot burner must be closed to prevent a buildup of gas within the appliance and the possibility of a fire or an explosion. As a result, conventional gas-fired appliances typically include a safety mechanism that detects the presence of the pilot flame and closes the valve between the fuel source and the pilot burner if the pilot flame is extinguished. One conventional safety mechanism incorporates a thermopile disposed proximate the pilot burner. The thermopile generates an electrical current in the presence of the pilot flame and the current is used to control the opening and closing of the valve between the fuel source and the pilot burner.
Conventional gas-fired appliances also typically include an exhaust vent or flue to direct emissions resulting from combustion away from the combustion chamber and into an area, such as the outdoors, where the emissions can dissipate. Exhaust vents, however, also allow heat to escape from the appliance thereby reducing the efficiency of the appliance. As a result, conventional gas-fired appliances typically include dampers disposed within the exhaust vent. The damper opens prior to ignition of the main burner to allow emissions from combustion to be evacuated from the appliance. When the main burner is extinguished, the damper closes to trap the remaining heat.
Conventional gas-fired appliances suffer from several drawbacks. The use of dampers and other electrically-actuated components within conventional appliances has often necessitated connecting the appliance to an external power source such as an A.C. power line. For example, many conventional appliances use a motor to open and close the damper wherein the motor is powered by an external power source. As a result, conventional appliances require additional components, are relatively expensive, and are dependent upon external electrical power even when sufficient fuel gas is present for operation of the appliance.
There is thus a need for a device for controlling a gasfired appliance that will minimize or eliminate one or more of the above-mentioned deficiencies.